Author(s) |
Saad Khairallah, Aiden A. Martin, Jonathan R. I. Lee, Gabe Guss, Nicholas P. Calta, Joshua Hammons, Michael H. Nielsen, Kevin Chaput, Edwin Schwalbach, Megna N. Shah, Michael G. Chapman, Trevor M. Willey, Alexander M. Rubenchik, Andrew T. Anderson, Y. Morris Wang, Manyalibo J. Matthews, Wayne E. King |
Abstract Scope |
We used ALE3D high-fidelity multi-physics model, which was verified with in-situ X-ray and other diagnostics experiments, to study laser-powder and laser-melt pool interactions at short time scales. We captured different modes of laser powder interactions that involve laser expulsion of spatter and laser shadowing (spatter blocking the laser rays). We report on self-replicating spatter, that once formed, become hard to get rid of due to a self-replication mechanism that involves loose particles in the powder layer. We explain how pre-sintering the powder could be a strategy to mitigate this effect. Spatter beyond a size threshold can cause pores due to laser shadowing. We identified the laser scan strategy as one source of these large spatter sizes and derived a stability criterion to prevent them. Work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE- AC52-07NA27344. Lawrence Livermore National Security, LLC. Release LLNL-ABS-799067. |